Brake-magnet protective and demagnetizing device.



UNITED sTATas PATENT oFFIoE.

DAVID L. LINnoUIsr, or YoNnEns, NEW YORK', Assis-Nor. To ons nLnvA'roa coM- vPANY, 0F JERSEY CITY, NEW JERSEY, A CORPORATION OF` JERSEY.

BRAKE-MAGNET PROTECTIVE AND DEMAG-NETIZINGVDEVICE. l

Specification of Letters Patent..

Applicatipn led latch 27, 1909. Serial No. 486,102.

4Yonkers, in the county of Westchester and State of New York, have invented a new and useful Improvement in Brake-Magnet Protective and Demagnetizin Devices, of whichthe following is a specication.

My invention relates to a device and arrangement for protecting the coils of an alternating current brake magnet, and for demagnetizing the brake magnet when the brake'is applied.y Although my invention is herein described as applied t'o a. two-phase three-wire motor, it may be used in conjunction with a moto-r of any number of phases, or connectedin parallel with any .inductive circuit of higher inductance than the brake winding `One of the objects of my invention is to rovide a fuseless device #for protecting rake magnet coilsvfrom bur out.

A further object is to provi e means for Y automatically demagnetizmg the brake magnet when it 1s denergized.

A still. further object is to vice of this character vwhich shall be simple,

' durable and cheap, and effective and eilicient y circuit with thewindings of the motor M.

'The operating switch P is providedwith a inoperation.

For the attainment of these ends and the accomplishment of other new and useful ob'- jects, my' invention `consists in the features of novelty in the. construction, combination matic means.

and arrangement of the several parts hereinafter more specifically described andclaimed in the appended' claims.

Inl the accompanying drawing, Figure 1 illustrates an embodiment of my invention applied to a two-phase three-wire brake and motor. Fig. 2 is a side view of a brake of the type preferably employed. i

My `invention obviates ythe necessity of using fuses to protect the brake magnetwinding from burning out. Theuse of fuses is always attended vwith an element of chance 4in their operation, and destruction'of the fuse when it does operate.

My invention is designed toprotect, at all times, the brake magnet winding from burning out, and to effect the demagnetiz'ation of the brake' whenever' the .supply switch is opened, either ,Rete to av twothreewire inlhntalnation o inventildn is shown by manual-means or autoprovide a de- `winding 15 to `wire 25;thenc e through 29, .wire 1 1'.z When the contacts 29 and 31 are separated-,or the switch S is opened, the cir- 110. n

in connection with a brake B, and a motor M. The motor M and the brake B are preferably ofvwell known design and construction. The vbrakei (Fig. 2) comprises brake shoes 18, 19,1)1aced' about a brake pulley 39 ;v the brake shoes v18 1S) are lifted when the 'brakefis energized. The cores 20, 21 move toward each other in the well known man'- ner when the magnet is energized, and it takes much less current to retain the cores tuate them in t eviirst place. In case the cores 20, 21 are too vfar apart the current taken by the brake magnet windings 14, 15 isk several times the ordinary holding cur rent, and may `be suilicient` to burn out the said windings if adequate protection is not made. But when the magnet is energized the cores 20, 21 are drawn near together, and the holding current through the brake magnet windin is reduced to a minimum.

Again re rring to Fig. 1,the motor `M is connected to the mainsi12, 13 'through the two-pole switch S, Wires 37, 38, operatiin 80 switch P, motor leads 22, 2.3, to the motor and the common return Wire 11 is connected 'l directly to the motor M. The brake windingcoils 14,' 15 are connected in a parallel -ne'cted in series with the magnet'winding 27 ofthe protective device; the circuits may be traced as follows: ,from motor lead wire 22, through wire 16 and brake magnet winding 23, through' wire .17 and' brake magplt e common wire 25, magnet winding 21, and

Wire`26 to the. common return wire 11, Thus 10h it is seen that the motor windin andthe brake magnet windings 14, 15 are 1n' parallel' circuits. ,l

The operating switch magnet coil circuit is traced as 36, wire 26, to the common return PatentedNov.5.1912.

. 20, 21 1n thelr operated position than to ac- 14 to the wire 25, and from motor lead wire follows: 'from the main '13', 16.5 throughv the switch S, wirev 38, swltohfcon-y tact 34, magnet coil 24, wire 3,5, cont-acts 31,'. y

stops 41 and 42;

cuit through the magnet coil is opened, and the operating switch P opens automatically.

The brake protecting device A comprises a magnet winding 27, a core 40 movable therein, and adapted to be attracted by current flowing in the winding 27. 'This core i moved the lever 44 follows, keeping the con- -tacts 29, 31 in electrical connection; but

when the attraction caused by current flowing in winding 27 is suicientl great the lever 28 is moved so far that the lever 44, in following, strikes the stop 42, and can go no farther, whereby the contacts 31, 29 are separated.

rEhe weight Wv is placed on the lever 28 tomake the movement of the lever sluggish in action, and this lever is so adjusted with .respect to the magnet winding 27 that the ordinary current wing through the magnet w1nd1ng 27 ywill not cause sufficient movement of the lever 28 to separate con-k tacts 29and 31. But if, for anyreason., the

current taken by the brake windings 14, 15

is so far in excess of the normal current thereof, and continues for such a time as to .endanger the brake windings 14, 15,'thelever 28 will be attracted suiiiciently to part -the contacts 29 and 31, the lever 28 will be caught by the shoulder 33 of the pawl 32 which is in tension caused bythe spring 45,

' and the lever 28 will be prevented from reconnecting the contacts 29 and 31 until it is released from the shoulder 33. Separation of the contacts 29 and 31 breaks the circuit including the magnet coil 24, thereby allowing the operating switch P to open, which breaks the circuits to the motor M and to the brake B, causing the motor to be stopped. The coil spring 30 may be so adjusted as to .vary the pressure'of the contact 31 against contact 29 and lever 28.

lt'has been found thatrwhen two inductive devices are connected in parallel, as'for instance the motor M andthe brake B shown in the accompanying drawing, the higher inductance discharges through the lower when the current supply to both is broken, thereby exerting a dmagnetizing influence on the lower inductance. That is, if the motor M is in operation and the brake' coils 14, 15 are receiving current, the ings and the brake coils are in arallel circuits, as previously explained; ifeither the switclf S or the operating switch is openem the inductance of the motor wind' "current supply, A lthe brake magnet and permits struction,

'rions changes may motor wind-V ings overcomes the lower inductance of the brake windings, Vand demagnetizes the brake magnet. The advantage of this demagnetizing action is to assist in applying the brake B when the supply current is cut off by the manual opening of' switch S or operating switch P. The circuit through the motor and brake during the demagnetization is deemed sufficiently clear not to warrant a detailed description.

'To start the motor,both the manual switch S and the operating switch Pmnstlglosed.

The lbrake magnet will`then,be energied,"

and the cores 20, 21 drawn together to release the brake pulley wheel 39.

The current taken by the brake magnet windings 14 and 15 passes through the magnet coil 2 7 in series with the said windings, but the current is not ordinarily suicient to operate the pivoted armature lever 28. The contacts 29 and 31 close the circuit through the operating switch holding coil 24. The action of thebrake magnet protecting device A may be adjusted to suit various conditions, by 'varying the position or size of the weight YV, and by varying the tension of the spring 30 on the contact 31 which bears against the contact 29. The automatic opening of tlie operating switch l? by the action of the safety device or the manual opening of the knife switch S cuts off the automatically demagnetizes the brake to be applied and stop the motor. Y.

It is to be understood that although my invention is described as applied to a brake magnet, itmay be used in connection with any two or Imore inductive 'devices in parallel, when the current through one o r more of them is subject to changes; my invention is suitable both for protecting the devices from too great a Acurrent and also for demagnetizing them.

I desire not to be limited to the exact concombination and arrangement of the several parts,

be made by' those vskilled in the art without departing from the spirit and scope of the invention; but

What l claim and desire to secure by Letters Patent of the United States is 1. In combination, an alternating current brake, an alternating current'motor, means for supplying current to the two in parallel, and means dependent for operation upon the current through thebrake for cutting off the means of current supply to themotor .and brake without altering the connections as it is evident that val parts for breaking-the said connections with? out destroying said parallel connection.

3. The combination of an alternatin current motor and an alternating current rake of unequal inductance connected in parallel, means for supplying current thereto, and

electro-responsive means controlled by cur-- rent in the brake magnet circuit for breaking the supply of current tolitheinotor and the brake and permitting the induced cur` rent of the motor to flow through the brake magnet Windin s. i

4. Thel combination with current supply mains, of an operating switch, an alternat-v ingcurrent motor and a brake connected in paiallel, an electro-magnetic lprotective device operative to open 'the operatingswitch when the current through the brake winding is a predetermined amount.

5. The co-mbination -\vith current supply mains, of an alternating current brake, a

`motor connected inv parallel therewith, an

operating switch to connect the motorand brake to the supply mains, anl electro-responsive device responsive to current in the brake magnet circuit and operative to open the operating switch, thereby permitting the inductive current of the motorl to iow through the brake windings to demagnetize the brake.

6. 4The combination with current supplyA mains, of an alternating current brake, an alternating current motor,'a manual switch,

an operating switch, an electro-magnetic protective device connected 1n series ,with the brake windings and operative to effect the opening of the operating switch, and

parallel circuits connecting the brake andY motor when the switches that connect the brake and the motor to the mains are openor closed, thereby permitting the inductive current of the motor to discharge through `the brake when either of said switchesl are,

opened.

. 7. The combination of an alternating current brake, an alternating current motor, an

operating switch, a brake magnet winding protective device which is operative to open the operating switch when the current through th'e brake winding is too great, and a parallel circuit connecting the brake and the motor whereby the brake magnet is demagnetized when the operating switch opens.

8. The combination of a motor, a brake in conjunction therewith, a brake, magnet protective device havin(y aiiiagnet winding in series with the brahe'ma iet coils, an

operating switch automatical y opened by theelect-ro-responsive action of the protective device when tooy great a current flows 4in the magnet winding off the protective device.

9. The combination of 'al motor, a brake forjthe motor, an 'operating switch, .a brake magnet protective device having a magnet winding in series with thebrake magnetwindings, a lever adapted to beoperatively moved when too great a currentl flows inthe protecting device magnet winding, means for automatically breaking the` c1rcuit through the operating switch Vmagnet current motor, ofan valternating current coil when the lever is moved. l, 10. The combination with'an alternating brake, an operating switch, a magnet winding in series with the brake windin an armature core adapted to be operative y at tracted when an excessive current Hows through the magnet winding, means for auf tomatically opening the operating-switch to effect the stopping'of the vmotor andthe application of the brake when the armature core is operatively attracted. i

11. The `combination with an alternating Yat current motor, of a brake connectedjin ar allel, an operating switch, a ina et wind ing in series with the brake winding, an

armature attracted when the said magnetwinding receives current, means to varythe pull necessary oieratively -to attract the said armature, an means 1n connection with -the armature for automatically opening the operating `switch when the armature is 'o f erativelyy attracted thereby to protect yt e brake-winding without affecting its parallel v connection withthe motor;

l2. The combination with" an alternating current motor, ofl an alternating current brake, an operating switch',`a magnet Wind ing in series with the brake magnet winding,

e DAVID L, LiNDQUisi.

L Witnesss ROGER W. FLAGG, EDWARD H. STEELE.

Copies of thil patent may be obtained for ve cents each, by addressing the Commissioner .of `Patents,

Washington, D. C. l

its 

